By comparison, it took three months for the original Galaxy Note to reach the 3 million sales mark.

Samsung, the largest smartphone and mobile phone maker in the world, has driven growth partly through sales partnerships with 260 wireless carriers around the globe.

On Nov. 5, Samsung said it had sold 30 million Galaxy S 3 smartphones in its first five months on the market, showing that the 4.8-in. form factor of the S 3 is still more popular than the 5.5-in. Note II.

The Galaxy Note 2 also includes a digital stylus for use on its touchscreen.

Some analysts have been uncertain about the sales potential for both Note devices because they considered a 7-in. tablet form factor the smallest to be successful for viewing content.

At the same time, analysts acknowledge that Samsung seems to have tapped into a sizeable market with a Note device that merges the worlds of smartphones and tablets.

"The Note form factor works very well for many users who don't need a device that fits inside a pocket," said Jack Gold, an analyst at J. Gold Associates. "The 5.5-in. screen is a great size for Web surfing and videos. I even use it as a book reader and it fits in my shirt pocket pretty well."

As a large manufacturer, Samsung has shown a willingness to try out multiple mobile deviced form factors, analysts said. The company doesn't appear to be willing to sacrifice any potential sales for in-between sizes, analysts added.

"The Note strikes a good balance between smartphone and something more," Gold said. "I expect the Note-class device to continue to succeed in the market although it's not going to appeal to everyone. And that's OK."